Biodiversity on Abandoned Farmland: The Best of Both Worlds?

Tom Fayle Conservation Biology Group and Museum Room Group Department of Zoology, University of Cambridge Funded by the Eranda Foundation

1. Summary 4. Results Large areas of arable farmland are being abandoned in Europe and 4.1 Species richness so it has become of great importance to know what will happen to In general the abandoned farmland was home to greater numbers of species than the other habitats (Figure 2). For birds the abandoned farmland was marginally more species-rich than these areas if they are left unmanaged. Here I show that abandoned the woodland, and both were much more species-rich than the arable farmland or set-aside (Figure 3). In terms of trees the abandoned farmland and woodland were equally species-rich and there arable farmland can become a habitat with a high species richness were no trees on the arable farmland or set-aside (Figure 3). of , birds and trees, with species assemblages similar to both those of set-aside and those of mature woodland. In addition 4.2 Community composition such areas of abandoned farmland may provide habitats suitable for Where significant numbers of species were present in all four areas the community composition of the abandoned farmland was generally intermediate between that of the set-aside and that of the species of national conservation importance. woodland (e.g. Figure 4). The community composition of the arable farmland and the abandoned farmland were usually very different (Figure 4).

4.3 Species of conservation importance

2. Introduction A number of species of national conservation importance were found on the abandoned farmland. These were:

Between 1989 and 1997 an area of 30,000km2 of arable farmland • A nationally scarce ground beetle (Pterostichus macer) fell out of use in Europe (CEC 1998). Can these areas of • Two species of spider never before recorded in the county (Gongylidiellum latebricola and Pirarata uliginosus) abandoned farmland turn into areas of value to conservation if left Mating Six-spot burnet moths (Zygaena • Six species of bird with a UK Biodiversity Action Plan: Spotted flycatcher (Muscicapa striata), Bullfinch (Pyrrhula pyrrhula), Turtle dove (Streptopelia turtur), Song thrush (Turdus philomelos), Skylark filipendulae) on the abandoned farmland to develop without management? In order to answer this question I Marbled white ( galathea) on the (Alauda arvensis) and Linnet (Carduelis cannabina) compared the species present in four areas with different land-use abandoned farmland trajectories (Figure 1): • One species of mammal with a UK Biodiversity Action Plan: Brown hare (Lepus europaeus)

• Current arable farmland () 450 Wheat • Fifteen-year-old set-aside 400 Set-aside Wheat • Fifty-eight year-old abandoned farmland 35 Abandoned farmland 100100 a Set-aside 350 Wheat a • Secondary ancient woodland aa Wheat a Abandoned farmland Woodland 30 Woodland 300 9090 Set-asideSet-aside Previous work looking at the biodiversity of abandoned farmland in AbandonedAbandoned farmland farmland 25 a 250 Woodland the UK has focussed exclusively on the plants (e.g. Harmer et al. 8080 Woodland b Axis 3 200 2001). Therefore I decided to look at a wide range of taxonomic 20 b a 7070 a 150 groups. These were: bb 15 100 •Birds 6060 10 c 50 Total species richness (+SE) richness species Total • Trees 5050 5 b bcbc b 0 a a d c •Spiders c 0 100 200 300 400 500 4040 0 cc Axis 1 • Ground beetles aa Birds 18th May Birds 31st May Birds 27th June Trees a Figure 4. A detrended correspondence analysis of the beetle RTUs in the 3030 a abab Total species richness (+SE) richness species Total Total species richness (+SE) richness species Total Figure 3. The species richness of the birds and trees within each of the study different areas. Each point represents the community of a single sampling point. • Hoverflies a a a a bcbc areas. Within each taxonomic group, areas with the same letters do not have Points close together have similar communities while those far apart have a bb a 2020 a a significantly different species richness dissimilar ones. Similar results were obtained for the other taxonomic groups • a b cc a bbb b c abab b 1010 b c b b • Beetles bcbcb Figure 1. The four areas on which c surveys were carried out 00 BeetlesBeetles Carabids Lepidoptera LepidopteraLepidoptera LepidopteraLepidoptera SyrphidsSyrphids Spiders Spiders 5. Discussion May Aug (water May Aug (water Previous work on old-field succession has shown that plant species richness gradually increases over time (Begon et al 1996 p906). This does seem to be the case in my study, (transects) (transects)(transects) traps)traps) 3. Methods as the abandoned farmland and the woodland have similar numbers of tree species. But arthropod and bird species richness do not show the same pattern and are greater on Figure 2. The species richness of the various arthropod taxa within each of the study areas. Within each I surveyed the groups listed below from ten sampling points in each taxonomic group, areas with the same letters do not have significantly different species richness the intermediate-succession abandoned farmland than on the woodland. The communities present on the abandoned farmland were similar to both those found on the set-aside of the arable farmland, the set-aside and the woodland, and from and those found on the woodland. This gives a clue as to the reasons for the greater species richness of the abandoned farmland. With communities present that are twenty sampling points in the more heterogeneous abandoned characteristic of both set-aside and woodland it would seem that the abandoned farmland provides a wider range of habitats and therefore attracts a wider range of species than farmland. All individuals observed were identified to species, except either of these habitat types. in the case of the beetles which were identified to Recognised Taxonomic Unit (RTU). 6. Conclusion Abandoning farmland gives rise to a species-rich habitat which may also be colonised by species of national conservation importance. Therefore allowing abandoned farmland to

Study taxa Survey methods Frequency of surveys develop naturally is a viable strategy for the conservation of a variety of taxa. Birds Point counts Three times in May and June Trees All trees within 10m of each sampling point Once Acknowledgements References Spiders Pitfall trapping Continuous for one week The late Miriam Rothschild for allowing me to work on her land and making me feel welcome in her home Begon, M., Harper, J. L. & Townsend, C. R. (1996) Ecology (3rd ed.) Blackwell Science, Oxford Ground beetles Pitfall trapping Continuous for one week Ray Symonds for identification of my spiders CEC (1998) Agricultural situation and prospects in the central and eastern European countries (summary report). European Hoverflies Water trapping Continuous for one week Roger Morris for help with identifying syrphids Commission, Brussels Lepidoptera Transects and water trapping Three times between May and August Brian Eversham for help with fieldwork and carabid identification Harmer R., Peterken G., Kerr G. & Poulton P. (2001) Vegetation changes during 100 years of development of two secondary Beetles Sweep netting Once Spider (Araneus sp.) My supervisors William Foster and Rhys Green woodlands on abandoned arable land. Biological Conservation, 101, 291-304